set 14 MCQ Questions & Answers Detailed Explanation

Question : 1

The frequency of a wave travelling at a speed of 500 ms^–1 is 25Hz. Its time period is

a) 25 s

b) 20 s

c) 0.05 s

d) 0.04 s

Question : 2

The regions of compressions and rarefractions of sound wave are·establisbed because

a) the reflected sound wave at fixed end interferes with the incident wave

b) the sound wave undergoes diffraction behind obstacles

c) the longitudinal movement of air molecules produce pressure fluctuations

d) the speed of the sound wave changes as it travels through a medium

Question : 3

Wireless communication is reflected back to the Earth’s surface by the

a) Ionosphere

b) Stratosphere

c) Troposphere

d) Exosphere

Question : 4

Consider the following phenomena.

1. Size of the Sun at dusk
2. Colour of the Sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky

a) 1, 2 and 4

b) 3, 4 and 5

c) 1, 2 and 3

d) 2, 3 and 5

Question : 5

Water has maximum density at

a) –4°C

b) 0°C

c) 32°F

d) 4°C

Question : 6

Consider telecommunication through optical fibres. Which of the following statements is not true ?

a) Optical fibres may have homogeneous core with a suitable cladding

b) Optical fibres are subject to electromagnetic interference from outside

c) Optical fibres have extremely low transmission loss

d) Optical fibres can be of graded refractive index